UNLV researchers and colleagues may have identified the first known planet
to orbit three stars.
Unlike our solar system, which consists of a solitary star, it is believed
that half of all star systems, like GW Ori where astronomers observed the
novel phenomenon, consist of two or more stars that are gravitationally
bound to each other.
But no planet orbiting three stars—a circumptriple orbit—has ever been
discovered. Perhaps until now.
Takeaways
Using observations from the powerful Atacama Large Millimeter/submillimeter
Array (ALMA) telescope, UNLV astronomers analyzed the three observed dust
rings around the three stars, which are critical to forming planets.
But they found a substantial, yet puzzling, gap in the circumtriple disc.
The research team investigated different origins, including the possibility
that the gap was created by gravitational torque from the three stars. But
after constructing a comprehensive model of GW Ori, they found that the more
likely, and fascinating, explanation for the space in the disc is the
presence of one or more massive planets, Jupiter-like in nature. Gas giants,
according to Jeremy Smallwood, lead author and a recent Ph.D. graduate in
astronomy from UNLV, are usually the first planets to form within a star
system. Terrestrial planets like Earth and Mars follow.
The planet itself cannot be seen, but the finding—highlighted in a September
study in the Monthly Notices of the Royal Astronomical Society—suggests that
this is the first circumtriple planet ever discovered. Further observations
from the ALMA telescope are expected in the coming months, which could
provide direct evidence of the phenomenon.
"It's really exciting because it makes the theory of planet formation really
robust," Smallwood said. "It could mean that planet formation is much more
active than we thought, which is pretty cool."
Reference:
Jeremy L Smallwood et al, GW Ori: circumtriple rings and planets, Monthly
Notices of the Royal Astronomical Society (2021).
DOI: 10.1093/mnras/stab2624
Tags:
Space & Astrophysics